A process for enhancing the fluorine utilization of a process gas that is used in the removal of an undesired substance from a substrate is disclosed herein. In one embodiment, there is provided a process for enhancing the fluorine utilization of a process gas comprising a fluorine source comprising: adding a hydrogen source to the process gas in an amount sufficient to provide a molar ratio ranging from about 0.01 to about 0.99 of hydrogen source to fluorine source.